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Jan-2025

How to protect catalysts in switch to renewable feedstocks (NARTC 2025)

There is mounting public and governmental pressure on refiners to aid in the energy and material transition.

Taco van der Maten
Malvern Panalytical

Viewed : 996


Article Summary

One way to do this, while utilising existing resources and infrastructure, is to switch to renewable feedstocks, such as plastic waste and used fats, oils, and greases (FOG). However, there is a catch: renewable feedstocks are frequently unpredictable in content. They often contain high levels of oxygen, chlorine, and silicon, which can ‘poison’ the catalyst, raising costs, reducing the plant’s efficiency, and even forcing downtime.

With the right analytical techniques, it is possible to avoid these expensive process interruptions. Malvern Panalytical’s Epsilon 1 and Aeris instruments provide rapid, reliable, reproducible insights into the catalysis and feedstock materials, helping to protect the catalysts and bottom line.

Renewable feedstocks present an opportunity for refiners
The key drivers for the incorporation of renewable feedstocks into oil refineries are global regulations like the Renewable Fuel Standard in the US and the EU’s Renewable Energy Directive. These regulations legislate targets for oil producers when it comes to lowering their carbon emissions and producing fuels derived from renewable resources. Oil refineries must now move towards more sustainable practices or risk falling foul of legislators.

However, alongside regulatory pressure, renewable feedstocks also represent opportunities for profit. Many governments offer tax credits and subsidies for producing biodiesel or diesel made from renewable feedstocks. For example, in the US, the Biodiesel Tax Credit is $1 per gallon. Biowaste like FOG can be used to produce sustainable aviation fuel (SAF), which can earn you US tax credits thanks to the Inflation Reduction Act. In the EU, the Biofuels Program offers subsidies to increase the production of fuels derived from waste and residues. Pyrolysis using waste plastic also serves a dual purpose: addressing the depletion of fossil fuel resources and reducing the amount of plastic waste that goes to landfill or, even worse, ends up poisoning the oceans.

In short, switching to renewable feedstocks can help maintain compliance, provide financial benefits, and even help clean up the planet. However, there are obstacles in the way.

Catalysts under attack
Although renewable feedstocks can produce good-quality oils, the process of refining them can take a toll on equipment because they have a different elemental make-up compared to fossil fuels. Typically, FOG-derived feedstocks are relatively stable in terms of their composition but contain around 8-12% oxygen, plus impurities such as sodium, potassium, silicon, and phosphorus. Waste plastics, on the other hand, are highly variable and contain a high concentration of impurities such as halides, silicon phosphorus, alkali metals like sodium and potassium, and other metals like magnesium, calcium, nickel, and vanadium. The presence of these impurities has a degenerative effect on refinery catalysts, similar to the well-known nickel and vanadium catalyst poisoning effect.

Chlorine is another element that can be poisonous to catalysts, even in trace amounts. Like nickel and vanadium, chlorine can block the catalyst’s active sites during processes such as hydrocracking. This leads to reduced performance and even total inactivity of the catalyst if the situation goes untreated. To prevent this from happening and to access the benefits of renewable feedstocks, it is essential to gain enhanced insight into both the catalyst and feedstock materials.

Strengthen catalysis with Aeris XRD
One way to protect your processes is by strengthening the catalyst itself. This requires a detailed understanding of its molecular structure, crystallinity, and phase composition. X-ray diffraction (XRD) can help here. XRD techniques direct an X-ray beam through a powder, solid, or liquid sample and measure the signal from a wide array of angles to calculate information such as crystallite size and crystal phase. The benefits of XRD over other analysis types are that it is non-destructive and very quick to produce reliable results. The Aeris XRD instrument can yield reproducible results in as little as 10 minutes without needing a dedicated technician.

The Aeris XRD instrument can be used to analyse the structural integrity of the clays and binders in the catalyst and evaluate the overall content of the catalyst materials. This can help to ensure consistency in performance. The Aeris instrument can also deliver insights into the molecular structure of materials such as zeolite in the hydrocracking and refining processes. It helps to identify any structural distortions that could affect the catalyst’s acidity, silicon and sodium tolerance, and activity reduction. Factors like these are important to monitor because they affect the selectivity and reaction rates of the catalyst. Monitoring them can help detect catalyst poisoning before it grinds operations to a halt, allowing time to swap in fresh catalysis materials or develop more robust ones.

Analyse feedstock with Epsilon 1 ULS
Another method to protect the plant from unexpected downtime is to analyse the feedstock for impurities. X-ray fluorescence (XRF) is a good solution. Like XRD, XRF is a non-destructive technique; however, instead of revealing crystalline structure, it helps with elemental analysis. XRF works by irradiating a solid or liquid sample with X-rays and measuring the energy and intensity of the fluorescent X-rays emitted by the sample, each of which are distinct to different elements.

One of the challenges of elemental analysis in oil refining is that even traces of harmful elements like sulphur and chlorine can degrade the effectiveness of the catalyst. To truly protect the catalyst, a highly sensitive instrument is needed. The Epsilon 1 Ultra-Low Sulfur (ULS) XRF is specifically designed for ULS analysis, as well as for detecting trace elements of contaminants such as chlorine, silicon, nickel, and vanadium. The Epsilon 1 is ISO 13032 compliant, meaning that it adheres to the most stringent international test method for sulphur content measurement in fuels.

Empowered with this deep insight into the feedstock, it is possible to take action to adapt the feed, such as pretreating the feedstock to dechlorinate the materials. These insights could also be used to tailor the catalysis materials to the incoming resources. This could involve choosing a catalyst that is more chlorine-resistant, alloying or coating the catalyst materials to protect them from poisoning or, where possible, controlling the temperature of the reactions to lessen the degenerative effect on the catalyst.

Catalyse change in the oil industry with enhanced analysis
Catalyst poisoning is a risk when switching to renewable feedstocks, but it does not have to be an insurmountable obstacle. With sensitive analytics like the Aeris XRD and Epsilon 1 ULS instruments, it is possible to spot and stop catalyst poisoning before it costs time and money, protecting the catalyst, preventing downtime, and promoting more sustainable oil production.

This short article originally appeared in the 2025 NARTC Newspaper, which you can VIEW HERE


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